How long a recipe takes, especially this one more depends on your level of experience in doing it than anything else. Notice the recipe tells you how to adjust the thickness to your liking. The trial and error to learn exactly how much ingredient to use (water) consumes a lot of unnecessary time once you have become proficient at it. Once you know exactly how much water to use first time, you've knocked a lot of prep time off your cooking time.
Same with the heat of the cast iron pan. Once you know how hot you need your pan to do the sauteing, you no longer have to guess and adjust. You set the pan on the burner early and it's ready when you are. Each of these are one little trick you learn in the process.
The rice cooking normally takes 20 minutes. Nothing says you can't cook the rice at the same time on another burner. Making the gravy once you have it all down pat probably won't take more than 20 minutes so that about the time your rice is ready so is your gravy.
A lot times in the evening rather than munch on snack foods, we make grill cheese sandwiches. It takes me about 5 minutes from walking in the kitchen to first sandwich done. Mainly because of two things. Made so many of them, I have it down pat to a tee, knowing what to pull out first and what I need before I need it to have it on hand. The second item that speeds this process up, is there are two of us in the kitchen at the same time. While I am preparing the cooking utensils and gathering the other items, the lady is defrosting the bread, gathering the items I haven't gotten and by the time the sandwich is ready, everything unneeded has been put back up. You can't do this without the experience ahead of time of knowing what you need, when you need it, and how you need it on hand before you need it.